Question about rebuild !

[Pikix]

Hi everyone,
My d24t, who has more than 250k km (odometer broken) , has a very low compression (300 psi on one cylinder with a Chinese tester), my volvo is very slow and stalls (?? not sur about the word) very easy when engine is cold.
So I was thinking to rebuilt it, but an old mechanic specialized in volvo told me that change piston rings will be almost useless (cylinder oval with age)...

So I would know your thinking and if someone did a rebuilt of a high mileage d24 and the results you had (knowing that I m looking for a high performance engine 200+ hp)?


Thanks for your help